Table 2. MABr concentration effect on the typical photovoltaic parameters.

MABr concentration (mg ml−1)	Jsc (mA cm−2)	Voc (V)	FF	PCE (%)
0	20.54±0.07	1.052±0.027	0.724±0.012	15.64±0.63
1	21.27±0.47	1.092±0.010	0.735±0.019	17.06±0.67
2	21.86±0.12	1.120±0.010	0.754±0.020	18.50±0.39
4	21.48±0.28	1.056±0.005	0.734±0.014	16.66±0.48
8	21.27±0.16	1.049±0.011	0.665±0.031	14.83±0.47
Champion	21.60	1.120	0.793	19.12

FF, fill factor; MABr, methylammonium bromide; PCE, power conversion efficiency.

S.D.'s from 8 to 12 cells for each type of devices are given. For these devices, high-quality MAPbI₃ films (Fig. 3a) were used as the initial films prior to MABr treatment.